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July 2007

Pentachlorobenzene Sources, environmental fateand risk characterization

Robert E. Bailey

July 2007

SCIENCE DOSSIER

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July 2007This publication is the eleventh in a series of Science Dossiers providing the scientific community with reliableinformation on selected issues. If you require more copies, please send an email indicating name and mailingaddress to eurochlor@cefic.be.The document is also available as a PDF file on www.eurochlor.org

Science Dossiers published in this series:1. Trichloroacetic acid in the environment (March 2002)2. Chloroform in the environment: Occurrence, sources, sinks and effects (May 2002)3. Dioxins and furans in the environment (January 2003)4. How chlorine in molecules affects biological activity (November 2003)5. Hexachlorobutadiene sources, environmental fate and risk characterisation (October 2004)6. Natural organohalogens (October 2004)7. Euro Chlor workshop on soil chlorine chemistry8. Biodegradability of chlorinated solvents and related chlorinated aliphatic compounds (December 2004)9. Hexachlorobenzene - Sources, environmental fate and risk characterisation (January 2005)10. Long-range transport of chemicals in the environment (April 2006)Copyright & ReproductionThe copyright in this publication belongs to Euro Chlor. No part of this publication may be stored in a retrieval system or transmitted inany form or by any means, electronic or mechanical, including photocopying or recording, or otherwise, without the permission of EuroChlor. Notwithstanding these limitations, an extract may be freely quoted by authors in other publications subject to the source beingacknowledged with inclusion of a suitable credit line or reference to the original publication.

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Foreword

The Environmental Working Group (EWG) is a science group of Euro Chlor, which

represents the European chlor-alkali industry. Objectives of the group are to identify bothnatural and anthropogenic sources of chlorinated substances, study their fate, gatherinformation on the mechanisms of formation and degradation in the environment, andachieve a better knowledge of the persistence of such substances and communicate thesefindings to a wide audience in order to promote science-based decision making. The EWGoften uses external specialists to assist in developing reports that review the state ofexisting knowledge of the different aspects mentioned.

Dr. Robert E. Bailey is an independent consultant on environmental chemistry of industrialproducts. Prior to setting up his own business, he worked for The Dow Chemical Companyin environmental chemistry from 1969 to 1995. He was supervisor of the corporateenvironmental chemistry group from 1976 to 1990 studying all aspects of the fate ofdifferent industrial chemicals. Dr. Baileys recent work has focused primarily on the sources

and fate of chlorinated chemicals and the fate of chemicals used in the polyurethaneindustry.

Dr Bailey would like to acknowledge the useful contributions to chapter 5.5, Critical bodyburden, by Dr Paul Thomas, Manager Environmental Chemistry and Regulatory Affairs,Akzo Nobel Technology & Engineering, Arnhem, The Netherlands.

In Pentachlorobenzene Sources, environmental fate and risk characterization, Dr Baileypresents a comprehensive overview of currently available information on this substance.This Science Dossier presents a thermodynamically self consistent set of physicalproperties important to movement in the environment which is suggested for use in futurework. The physical-chemical properties of pentachlorobenzene which are important for theenvironmental fate of the substance are presented, covering degradation, bioaccumulation

and the distribution in environmental compartments. There are no uses of PeCB known atpresent and an extensive inventory of current emission sources demonstrates thatcombustion is the major contributor. A summary of measured concentrations and trends invarious environmental compartments, including biota, is presented, as well as a summaryof ecotoxicity data. Finally, the major findings are summarized in a concluding chapter.

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Summary

A thermodynamically self consistent set of physical properties important to movement in the

environment has been reported and is suggested for use in future work.Pentachlorobenzene (PeCB) is a semivolatile chemical with an overall half-life in theenvironment measured in years and capable of long range transport.

There are no large scale uses of PeCB at present. Current emissions of PeCB to theenvironment are estimated to be about 85,000 kg/year, based on published information.The largest sources appear to be combustion of solid wastes, 33,000 kg/y, and biomassburning, 44,000 kg/y, with industrial processes less important.

PeCB has been measured in many environmental media over the past 30 years. Low butdetectable concentrations of PeCB have been reported in sediments and biota in remoteareas all over the world. Concentrations of PeCB in the environment have declined overthe period of monitoring with a 90% decrease of PeCB concentrations in herring gull eggs

from Lake Superior, Canada.

To protect the general public for lifetime exposure, the toxicity of PeCB has been studied

and an oral reference dose of 0.8 g/kg body weight per day has been established by theUSEPA. The corresponding Canadian tolerable daily intake has been set at 0.5 g/kgbw/day. The toxicity of PeCB to aquatic organisms has a lowest reported sublethal effect

concentration of about 10 g/L for daphnids and amphipods.

Concentrations of PeCB in the environment are low and are expected to continue to dropwith improving technology and waste handling.

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Table of contents

1 Physical and Chemical properties ....................................................................42 Environmental Fate .............................................................................................6

2.1 Environmental Degradation ....................................................................... 6

2.2 Bioconcentration/bioaccumulation ............................................................ 7

2.3 Distribution in environmental compartments ............................................ 83 PeCB Sources in the environment ................................................................ 10

3.1 Industrial uses of PeCB............................................................................10

3.2 Byproduct formation of PeCB ..................................................................10

3.3 Combustion formation of PeCB............................................................... 12

3.3.1 Waste combustion ......................................................................... 12

3.3.2 Coal combustion ............................................................................13

3.3.3 Biomass combustion ..................................................................... 14

3.4 PeCB from degradation of other chemicals in the environment ......... 15

3.5 PeCB global emissions inventory............................................................ 154 Concentrations and trends of PeCB in the environment........................... 16

4.1 Atmosphere................................................................................................16

4.2 Water ......................................................................................................... 16

4.3 Sediments .................................................................................................. 18

4.4 Soils .........................................................................................................20

4.5 Biota ......................................................................................................... 20

4.6 Comparison of environmental concentrations with

emission and fate ...................................................................................... 26

4.7 PeCB in the Environment Summary....................................................275 Ecotoxicity 28

5.1 Aquatic........................................................................................................ 28

5.2 Plants ......................................................................................................... 30

5.3 Wildlife ......................................................................................................... 305.4 Soil toxicity.................................................................................................. 30

5.5 Critical Body Burden .................................................................................306 Conclusions....................................................................................................... 347 References ......................................................................................................... 34

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1 Physical and Chemical properties

PeCB is is a chlorinated aromatic hydrocarbon with the molecular formula C6HCl5. Its CAS

registry number is 608-93-5. The structural formula of PeCB is shown below. A summaryof the physico-chemical properties is given in Table 1.1

Cl

Cl

Cl Cl

Cl

Table 1.1. Physico-chemical properties

Property Value Reference.

Molecular mass 250.34

Melting point 84.6 C (Shen and Wania 2005)

Boiling point 277 C (Weast 1983)

Density of solid 1.8342 g/cm3

(Weast 1983)

Vapor pressure, solid, 25 C 0.29 Pa Calculated*

Vapor pressure, sub-cooled liquid, 25 C 1.0 Pa (Shen and Wania 2005)

Log octanol/water partition coefficient, 25 C 5.19 (Shen and Wania 2005)Water solubility, solid, 25 C 0.0027 mol/m

3(Shen and Wania 2005)

Water Solubility, solid, 25 C 0.68 mg/L (Shen and Wania 2005)

Henrys Law constant calculated. 25 C 72 Pa m3/mol (Shen and Wania 2005)

* Calculated by linear regression of the literature values used by Shen and Wania.

The properties of PeCB that are key to predicting its movement in the environment are itsvapor pressure (sub-cooled liquid) and partition coefficients between environmentalphases. Because the different partition coefficients are thermodynamically related, it ispossible to adjust values to reduce the likely errors in the individual values. The values

listed above from Shen and Wania are their final adjusted values where the literature hasbeen evaluated to derive a consistent set of the best partitioning values for each chemicalstudied. They also derived internally consistent energies of phase transfer for PeCB whichcan be used for calculating partition coefficients at different temperatures.

UA = 60.22 kJ/mol

UW = 16.39 kJ/mol

UAW = 43.83 kJ/mol

UOW = -25.11 kJ/mol

UOA = -68.94 kJ/mol

UO = -8.72 kJ/mol (Shen and Wania 2005)

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The physical properties values listed above have been used in the following modelcalculation. The level I model is a static slice of the world containing air, water, soil andsediments (Mackay 2001). This simple model shows where a chemical accumulates atequilibrium in the absence of any degradation processes or flow.

PeCB in Level I model

Air 13%

Soil 84%

Water 0.6%

Sediments 2%

The physical properties of PeCB suggest that it will strongly sorb to sediments and soil.Thus many studies have monitored the environmental distribution of PeCB by analysis ofsediments. Desorption of PeCB from Rhine River and Ketelmeer sediments was reportedto be very slow, 0.00022 h

-1, a half-time of over 4 months, with only a small fraction

desorbing rapidly (ten Hulscher et al. 2002).

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2 Environmental Fate

2.1 Environmental Degradation

PeCB, like most chlorinated aromatics, is not expected to hydrolyze under environmentalconditions (Boethling and Mackay 2000). PeCB photodechlorination has been reported insurfactant micelles using UV radiation at 254 nm as a method for treating contaminated soil(Chu et al. 2002). Mill and Haag reported photolysis of HCB in a water acetonitrile mixturein California summer sunshine with a half-life of 70 d, although they state that some of theHCB may have been lost by volatilization (Mill and Haag 1986). The UV absorption rangeof HCB extends above 300 nm so that there is some opportunity for environmentalphotodegradation. PeCB is expected to behave similarly. Indirect photolysis of HCB in thepresence of humic substances in lake water has been reported and a similar process maybe significant for PeCB (Grannas et al. 2003).

No convincing evidence of aerobic biodegradation of PeCB in the environment was found.During a biodegradation study of quintozene (pentachloronitrobenzene) which is used as afungicide, the fate of PeCB which was present as an impurity was also monitored (Beckand Hansen 1974). Beck and Hansen reported a half-life for PeCB in soil of 194 and 345days, an average of 270 days. These slow rates of reported PeCB degradation couldeasily have been losses by volatilization from the soil in their experiments. The results ofBeck and Hansen showed that PeCB was apparently formed as an intermediatedegradation product of quintozene as the concentration of PeCB increased during the first100 days of laboratory incubation before starting its slow decline. The observations byBeck and Hansen of PeCB in soils which had been treated over a period of years withquintozene is consistent with their laboratory data, i.e., conversion of some quintozene toPeCB and its slow removal from soil.

It is probable that PeCB can be biodegraded by the type of fungi that have been shown tobe able to biodegrade HCB and other highly chlorinated aromatics. There have been manyreviews of fungal capabilities and PeCB has not attracted specific attention (Aust andBenson 1998). For example, white rot fungi, Phanerochaete chrysosporium, was used in alaboratory incubation of contaminated soil with 100% removal of 1,2,3,4-tetrachorobenzeneand some of the other contaminants (D'Annibale et al. 2005). The contaminated soil onlycontained 1 mg/kg PeCB so the extent of its removal was not estimated. A large numberof fungal isolates were screened for their ability to tolerate and degrade HCB andpentachlorophenol in a highly contaminated soil (Matheus et al. 2000). Of the 36 isolatesscreened, 11 were able to grow in soil with greater than 2% HCB, however separate testswith carbon-14 labeled HCB showed less than 1% yield of carbon-14 CO2 after 128 daysincubation.

Dechlorination of PeCB by anaerobic bacteria has been reported by many workers (Tiedjeet al. 1987; Fathepure et al. 1988; Pardue et al. 1993; Ramanand et al. 1993; Pavlostathisand Prytula 2000; Brahushi et al. 2004). The dechlorination rate of PeCB was reported tobe faster than that of HCB in a system enriched for HCB degradation (Pavlostathis andPrytula 2000). The initial source of inoculum was contaminated sediment from BayoudInde, Louisiana, USA. They reported that the isomer distribution of tetrachlorobenzenes(TeCB) from dechlorination of PeCB was 91% 1,2,3,5-TeCB and 9% 1,2,4,5-TeCB. Someof the other reports indicated that alternative paths were preferred with different microbialsystems and they all agree that PeCB goes to a TeCB. Pavlostathis and Prytula reported ahalf-life for PeCB in their enriched system of 1.2 days. Brahushi et al. reported that HCBwas converted to PeCB and then to TeCBs as described above in arable soil (Brahushi etal. 2004). Simply saturating the soil induced native anaerobic microbial communities. Thedechlorination was delayed and reduced by addition of other organics such as straw.

Beurskens et al. reported the anaerobic dechlorination of PeCB to approximately equalamounts of 1,3,5-trichlorobenzene and 1,2,4-trichlorobenzene by a mixed inoculum derivedfrom sediments from the Rhine River in Lake Ketelmer (Beurskens et al. 1994).

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PeCB has been observed in sediments that have been dated more than 60 years earlier(Durham and Oliver 1983). Therefore, in spite of the laboratory evidence for anaerobicdehalogenation by anaerobic microorganisms from many sources, PeCB can persist formany decades in sediments such as those in Lake Ontario. Lake Ketelmeer in the

Netherlands accumulates much of the suspended solids that flow down the Rhine River.Beurskens et al. have proposed that HCB and the resulting PeCB have been anaerobicallydechlorinated in these sediments to 1,3,5-trichlorobenzene and 1,2- and 1,3-dichlorobenzenes (Beurskens et al. 1993) . They found that the concentrations of HCBand PeCB in the ca. 1970 portions of sediment cores taken in 1988 had much lowerconcentrations of HCB and PeCB than surface sediments collected in 1972. In addition,the sediment cores had increased concentrations of tri- and dichlorobenzenes presumablyfrom the anaerobic dechlorination. A half-life of about 7 years for HCB in these sedimentswas derived from the extent of decrease in its concentration. This same activity insediments was proposed by Bailey based on the work of Durham and Oliver (Bailey 1983).However, this interpretation was not supported by the authors (Oliver and Nicol 1983).

Wang and Jones studied the fate of PeCB in soils with and without added organic matter in

the form of sludge (Wang and Jones 1994). They report that the primary mechanism forPeCB loss from soil is volatilization. There is the potential for photodegradation on theexposed surface of soil as has been reported in solution. One can also suppose that someaerobic microorganisms will slowly metabolize PeCB over a period of years. Additionally,even in surface soils there can be anaerobic zones during extended rainy periods wherePeCB could be dechlorinated. In cold sediments, the presence of many other organicmaterials may delay and retard the rate of anaerobic dechlorination. Thus in the followingdiscussion of environmental fate of PeCB, its degradation half-life has been arbitrarily takenas 10 years in soils, sediments and water.

Degradation of PeCB in the atmosphere is expected to be primarily through reaction withOH radicals (Atkinson 1990). The estimated reaction rate of PeCB with OH radicals is0.0579 x 10

-12cm

3/molecule-sec at 25 C (USEPA 2004). This corresponds to an

atmospheric half-life of 185 days calculated assuming an OH radical concentration of 1.5 x10

6radicals/cm

3for 12 hours per day, a diurnally averaged concentration of 0.75 x 10

6

radicals/cm3

(USEPA 2004). However the average tropospheric temperature is less, 277K, so its atmospheric half life will be greater. No activation energy for the reaction of OHradicals with PeCB was found but if it is assumed that the activation energy is about thesame as that of HCB, 24.3 kJ/mol (Brubaker Jr. and Hites 1998), the predicted half-life ofPeCB in the atmosphere at 277 K is about 370 days.

2.2 Bioconcentration/bioaccumulation

Bioconcentration describes a chemicals tendency to be taken up by an animal from water

solution. Bioaccumulation is uptake from both water and food. Van de Plassche et al.summarized bioconcentration (BCF) and bioaccumulation factors (BAF) for PeCB with fewdetails given (van de Plassche et al. 2001). Most of the studies are described in moredetail below. The reported BAF for PeCB in bluegill sunfish (Lepomis macrochirus) was3400. In rainbow trout (Oncorhynchus mykiss) a BAF range from 4000 to 8400 and inguppy a BAF of 13,000 are reported by van de Plassche et al. The much higher BAFvalues, based on concentration only in lipid, 155,000 to 260,000, also included by van dePlassche et al. should not be compared with the whole body BAF values used forregulatory purposes.

The BCF of chlorobenzenes in guppies (Poecilia reticulata) gave a calculated BCF forPeCB of 4,700 from its uptake and elimination kinetics (Van Hoogen and Opperhuizen1988). The fish were exposed for 5 days without feeding and the uptake of PeCB

determined followed by elimination of the PeCB in freshwater for 21 days. Another study ofthe PeCB BCF in guppies as a function of temperature reported lipid basis BCF valuesranging from a log of 5.11 at 286 K to 5.28 at 306 K (Opperhuizen et al. 1988). The

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guppies were 52% lipid so that these BCF values can be compared with the whole fishvalues above by multiplying by 0.05 to get a range of 6,400 to 9,500.

Detailed studies of PeCB uptake were conducted to determine lethal body burdens ofchlorobenzenes in the amphipod Hyalella azteca (scuds) and fathead minnows

(Pimephales promelas) (Landrum et al. 2004; Schuler et al. 2007). The average BCF,derived from the study of scuds at the five lowest concentrations tested, was 1900 with upto 28 days exposure. Higher exposure concentrations yielded lower BCF values for thescuds. Exposure of the minnows to PeCB for 28 days gave an average log of the whole-body BCF of 3.07 which equals 1175.

Bioconcentration of a mixture of chlorobenzenes at low concentrations in 250 g rainbowtrout (Salmo gairdneri, now Oncorhynchus mykiss) was studied (Oliver and Niimi 1983).They reported BCF values for PeCB of 13,000 and 20,000 after 119 and 105 daysexposure, respectively. These results led to predicted concentrations of PeCB in LakeOntario trout which were close to those found in the field. They stated These results wouldstrongly suggest that, excluding HCB, the chemical concentrations [of chlorobenzenes] inthe water largely control the concentrations in fish for these chemicals.

(Carlson and Kosian 1987) studied the bioconcentration and toxicity of PeCB to embryoand juvenile fathead minnows (Pimephales promelas). After 31 days exposure to PeCBthe average BCF was reported to be 8,400.

An extensive field study using samples collected from 1982 to 1986 in Lake Ontario andselected tributaries examined the concentrations of PeCB, HCB and other chlorinatedchemicals in a variety of environmental samples and biota (Oliver and Niimi 1988). Thisstudy is hard to interpret quantitatively because fish and water samples were collected atdifferent times from different locations. However, bioaccumulation factors (BAF) for PeCBfor several aquatic organisms representing different trophic levels, including several troutspecies, can be calculated from the results presented in their publication. PeCBconcentrations were 7215 pg/L in water, 8.46.5 ng/g wet weight in mysids, 5.03.7 ng/g

ww in amphipods, 2.6 ng/g ww in sculpin, 2.1 ng/g ww in large smelt, and 5.03.1 ng/g wwin large trout. The BAF for PeCB in trout can be calculated from this data as (5.0 ng/g)/(72pg//L) = 69,000 L/kg. Similar concentrations of PeCB at different levels of the food webshows a minimal effect of PeCB uptake from food.

A field study of PeCB concentrations in the industrially polluted Bayou dInde, Louisiana,USA reported apparent average log BAF values on a lipid basis (Pereira et al. 1988).These lipid basis values have been converted to whole-body BAF values by multiplying bythe reported lipid percent in the different species. The calculated whole-body BAF valuesin fish were: Atlantic croaker (Micropoganias undulates) 18,700: spotted sea trout(Cynoscion nebulosis) 2,100; blue catfish (Ictalurus furcatus) 12,300. The calculated BAFin blue crab (Callinectes sapidus) was 6,600. A later study in the same area usingsamples collected in 1990 gave similar BAF values but the lipid contents were not reported

so that whole-body BAF values could not be calculated (Burkhard et al. 1997).

2.3 Distribution in environmental compartments

Degradation of PeCB in different environments is described above. However, extrapolatingfrom laboratory conditions to define the expected environmental degradation rate involvesmany approximations. The most effective way to look at the fate of a chemical in theenvironment is to consider not only its degradation rate in each compartment of theenvironment but also its partitioning between compartments. This way one can estimate anoverall degradation rate or half-life (lifetime).The level III model adds degradation processes, plausible transfer rates between phases,

and PeCB flow into and out of the model space to the partitioning based on physicalproperties (Mackay 2001). Using the half-lives above, 370 days in the atmosphere and 10years in soil, water and sediments, and assuming all PeCB is emitted into the atmosphere,

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the percentages of PeCB accumulating in each compartment and degrading in eachcompartment are:

Compartment Percentage of PeCB

accumulated

Percentage of PeCB

degradingAir 30.6 81

Soil 68.1 18

Water 0.2

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3 PeCB Sources in the environment

No global inventory of possible emissions of PeCB to the environment was found.

However, in Canada total releases of PeCB have been estimated to be 41.8 kg/y. PeCBfrom backyard trash burning is estimated to be 21.93 kg/y, pentachlorophenol treatedwood, 2.34 kg/y, pesticide use 6.2 kg/y, dielectric fluid 5.6 kg/y, municipal solid wasteincineration 2.36 kg/y, hazardous waste incineration 1.84 kg/y, magnesium production 1.53kg/y and solvent use 0.04 kg/y (Environment Canada 2005). No estimates of PeCBemissions in the remainder of the world were found . Thus, the following factors forestimating global PeCB emissions were developed for this report

3.1 Industrial uses of PeCB

PeCB is not known to have any commercial uses at present (Beck 1986; EnvironmentCanada 1993). However, in the past, PeCB was one component of a chlorobenzenesmixture used to reduce the viscosity of PCB products employed for heat transfer(Environment Canada 1993; King et al. 2003). PeCB has also been used in achlorobenzenes mixture with PCBs in electrical equipment (Environment Canada 2005).PCBs are still in use in some old electrical equipment in North America and Europe so thatthere is a small potential for release of PeCB from this source (AMAP 2000; EnvironmentCanada 2003). It can be presumed that some PCBs are also still in use elsewhere in theworld and some fraction of them contain PeCB.

PCBs are being taken out of service in many countries of the world so that any relatedPeCB emissions are expected to be decreasing with time. Global releases of PCBs havebeen estimated to be approximately 40 metric tons in 2000 (Breivik et al. 2002). Breiviknoted a high level of uncertainty in the emissions estimate, plus and minus a factor of 10.Breiviks estimate of Canadian PCB emissions was 0.6 metric tons per year. Assuming thesame ratio of PeCB emission to PCB emission, the global emission of PeCB from use withPCBs can be roughly calculated:

((5.6 kg/y PeCB)/(0.6 t/y PCB))*(40 t/y PCB) = 373 kg/y

PeCB was used in the past as an intermediate in manufacture of pentachloronitrobenzene(quintozene) (van de Plassche et al. 2001). However, quintozene is now made bychlorination of nitrobenzene (Feiler 2001). PeCB may also have been used in the past as afungicide and flame retardant (van de Plassche et al. 2001).

3.2 Byproduct formation of PeCB

The U. S. Toxics Release Inventory (TRI) includes PeCB. A total of 20 industrial facilitiesare listed as emitting or transferring 2533 pounds (1151 kg) of PeCB in 2004 (USEPA2006). The industries represented are chemical, waste treatment, and coal burning electricpower. Total reported air emissions were 220 pounds (100 kg) and water emissions of 17pounds (7.8 kg) (USEPA 2006). In industrial chlorination reactions it is possible to producePeCB as a byproduct and it probably accounts for some of the emissions reported in theTRI. There are other processes which produce a variety of chlorinated aromatics that maycontribute PeCB even if PeCB has not been explicitly detected and reported yet. TRIincludes only industrial facilities handling relatively large amounts of chemicals so thatadditional emissions are expected.

One way to estimate global emissions from the global chemical and related industry sectorscovered by the TRI program in the USA is to simply multiply by the ratio of world grossdomestic product (GDP) to the US GDP. Since the USA accounts for about 25% of worldGDP, multiplying the TRI reported emissions to air and water by 4 leads to estimated global

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emissions of 431 kg/y. This value is uncertain because of both the uncertainty in the USemissions and waste handling practices in developing industrial countries. North Americanemissions of PeCB were greater in the past due to less stringent waste handlingregulations as shown by monitoring studies described in Section 4.

Global emissions from chlorinated solvent use and pesticide use have been estimated byscaling from the Canadian emissions reported by Environment Canada (EnvironmentCanada 2005). In round numbers, the Canadian GDP is about 2.5% of the global GDP.Therefore, multiplying the PeCB emissions from the use of chlorinated solvents, 0.04 kg/y,by 40 gives an estimate of 1.6 kg/y for global emissions from chlorinated solvents.Emissions from pesticide and pentachlorophenol use are calculated similarly:

(6.2 + 2.34 kg/y)*(40) = 341.6 kg/y

The emission of PeCB has been reported from the use of hexachloroethane (HCE) toremove dissolved hydrogen from molten aluminum in foundries (Westberg et al. 1997).

They reported an emission rate of 310 g PeCB/g HCE used at a typical HCE application

rate. While the use of HCE for degassing aluminum in foundries is not widespread in the

USA, several small foundries were reported to use HCE (Streeter 1998). Because HCE iseasier to use than gaseous chlorine for degassing aluminum, it is probably used in some ofthe less developed countries as well as in smaller facilities in developed countries. In 1998it was reported that about 3,500,000 kg/y HCE was used in this application (ScottishChemical 1998). Using the Westberg et al. factor, this could result in the emission of:

(310 g/g)*(3,500,000 kg/y)*(10-9

kg/g)*(1000g/kg) = 1100 kg/y PeCB.

Vogelgesang also reported the release of PeCB and other compounds from degassing ofaluminum (Vogelgesang 1986). PeCB emissions from an aluminum smelter using a

sodium/potassium chloride flux were reduced from 18.05 g/m3

to 10.34 g/m3

by

installation of a baghouse filter (Aittola et al. 1996). The other chlorobenzenes andchlorophenols were reduced by a similar fraction. In contrast, the filter reduced thepolychlorinated dioxins and furans by 98-99%.

There are several processes for production of metals involving the treatment of ores withcarbon and chlorine to yield a soluble or volatile compound which can be purified.

Carbochlorination of magnesium oxide, heating MgO with coke to 700-800 C in a chlorine

atmosphere, yields MgCl2 and CO along with traces of PeCB, HCB and dioxins/furans andother chlorinated compounds (Knutzen and Oehme 1989). Knutzen and Oehme estimatedthat about 50 kg/year PeCB along with up to 300 kg HCB may have been emitted to theFrierfjord, Norway during the 1980s (Knutzen and Oehme 1989). Norwegian regulationscalled for dramatic reduction in dioxin/furan emissions in the 1990s so that it may beassumed that PeCB emissions have decreased also (although not necessarily in directproportion). Recovery of copper from a slag by roasting it with coal and sodium chlorideproduced a variety of highly chlorinated organics (Doering et al. 1992). The residue from

this process was an attractive red gravel which was used in landscaping. Concentrationsof PeCB in this red slag ranged from 0.6 to 1200 g/kg and HCB ranged from 5.3 to 11000

g/kg in samples. Vogelgesang reported release of PeCB and other chlorinated

compounds from the production of niobium and tantalum (Vogelgesang 1986). The authorof this report, Bailey, speculates that other processes which use chlorine and carbon athigh temperatures may produce PeCB, such as the chloride process to produce TiO2pigment. No quantitative estimates are provided because there is no quantitativeinformation on which to base them.

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3.3 Combustion formation of PeCB

The observation of PeCB as a trace product of incomplete combustion has been widelyreported. Nearly all fuels contain some chlorine, especially biomass and waste. The yield

of PeCB from combustion of different fuels under different conditions has been reported tovary widely. The goal in this section is to extract PeCB yield factors from the variousresearch studies and apply these factors to combustion processes for estimation of globalPeCB emissions from combustion.

3.3.1 Waste combustion

Open burning of household waste and the resulting emissions of PeCB averaged 0.076(range 0.033-0.162) mg/kg mass actually burned or a factor of 7.6 x 10

-8kg/kg (Lemieux

1997). The variation between duplicate burns in this small project prevent any conclusionsfrom the two different waste mixtures used and illustrate the uncertainty in the emissionfactor. This study was designed to represent uncontrolled combustion of solid waste in aperforated barrel. It probably applies to much of the uncontrolled burning of trash which

takes place in piles all over the world as well as landfill fires.

Emissions of PeCB and other chlorobenzenes during incineration have been studied as apotential way to estimate emissions of chlorodioxins and furans (PCDD/F) with simpleranalytical technology. The use of PeCB for monitoring has been suggested by Kato andUrano who found a correlation between PeCB concentrations and the international toxicequivalent factor (I-TEQ) in 5 different operating waste disposal plants in Japan (Kato andUrano 2001). They found that under normal operating conditions PeCB correlated with I-TEQ within a factor of 3.

Other workers have also reported correlations between the emission of PeCB andpolychlorodibenzodioxins and furans (PCDD/F) (Oberg and Bergstrom 1987; Kaune et al.1994). Aittola et al. pointed out that a filter that removed over 90% of the PCDD/F,removed only about 50% of PeCB and HCB from an aluminum smelter (Aittola et al. 1996).Thus reductions in PCDD/F emissions may not lead to equal reductions in PeCBemissions.

The reported yields of PeCB to HCB formed in different combustion processes vary widely,depending on combustion conditions and the presence (or not) of catalytic materials. Forexample, in a fluidized bed solid waste incinerator the yield of total chlorobenzenes andPCDDs increased 20 fold as metals accumulated in the sand, while the PeCB/HCB ratiowas approximately the same (Akimoto et al. 1997). Because combustion conditions, forexample, oxygen, time and temperature, seem to dominate in most situations, the influenceof fuel composition, concentration of chlorine beyond a minimum concentration, on thePeCB emissions is only one of several factors.

Many of the studies of trace products of incomplete combustion report in terms of mass pervolume of stack gas which is what the regulations require. To convert to a yield of PeCB interms of mass of waste burned, a gas flow of 7,000 m

3/metric ton has been used

(Carpenter et al. 1986). Combustion experiments are difficult to control and the PeCB fromnominally duplicate runs varied by factors of 2 to 5 in those studies where replicates werereported. The variety of parameters studied also led to wide variation in the PeCB yields.Table 3.1 has only average PeCB yields and illustrates some of the variation reported. Theyield of PeCB is certainly affected by poor combustion conditions. Another significantfactor in the overall yield of chlorinated aromatics is the presence of solid surfaces,especially if metals are present. One conclusion from all this work is that PeCB is probablyemitted from all combustion processes of fuels containing any chlorine as organochlorine orchloride.

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Table 3.1. Yields of PeCB in various waste incineration experiments. The results ofdifferent experiments in each study have been averaged. PeCB concentrations have beenconverted to emission factors by multiplying by 7000 m

3of stack gas per ton of fuel.

PeCB Emission

Concentration

PeCB

Emission

Factor

Experimental Study

0.91 g/std m3 6.4 mg/ton Lab fluidized bed (Wikstrom et al. 1999)

39 g/std m3 273 mg/ton City incinerator (Tiernan et al. 1983)

1 g/std m3

7 mg/ton 24 city incinerators (Kato and Urano 2001)

23 g/std m3 161 mg/ton Lab fluidized bed (Fngmark et al. 1993)

12 g/std m3 84 mg/ton Lab fluidized bed (Fngmark et al. 1994)

0.42 g/std m3 2.9 mg/ton City incinerator (Jay and Stieglitz 1995)

25 g/std m3

175 mg/ton City fluidized bed (Akimoto et al. 1997)

2 g/std m3

14 mg/ton Hazardous waste

incinerator

(Oberg et al. 1985)

Special purpose experiments not used in waste combustion averaging.

87 ng/std m3

0.6 mg/ton Wood burner (Zimmerman et al. 2001)

969 mg/ton Pure PVC in pilot plant

burner

(Ahling et al. 1978)

300 mg/ton Pure PVC in lab burner (Kim et al. 2004)

The range of PeCB yields above extends over a factor of 100 from experiments designedto clarify the processes taking place during municipal incineration. The geometric mean ofthe emission rates from the waste combustion experiments above, except the Tiernan 1983study, is about 25 mg/ton. For the purpose of an order of magnitude estimate of PeCBemissions, the emission factor for municipal and hazardous waste incineration will be 25mg/ton of waste or 2.5 x 10

-8kg/kg. The total amount of waste incinerated with the low

emission factor above is estimated to be about 200 million tons per year which could yieldPeCB.

(2.5 x 10-8

)*(200 x 106

tons) = 5 tons = 5000 kg/y PeCB emitted.

In most of the developing world trash is burned casually to reduce its volume and attractionof vermin. The production of solid waste is estimated to be about 0.4 kg per capita-day

(Zurbruegg 2003). For this report it is estimated that about half of the solid waste isburned. Thus a population of 5 x 10

9people would generate 2 x 10

9kg/day of total solid

waste. Using the average PeCB emission factor from Lemieux, see above (Lemieux 1997),the yield of PeCB on an annual basis would be:

(2 x 109

kg/day)*(365 d/y)*(0.5 burned)*(7.6 x 10-8

) = 27,740 kg/y

3.3.2 Coal combustion

Coal use in 2005 was estimated to be 4990 million metric tons (World Coal Institute 2006).Coal typically contains about 0.1% chlorine. No information on PeCB emissions from coal

combustion was found. However 0.07 g/std m3

HCB has been reported from coal

combustion in a lab experiment (Oberg and Bergstrom 1985). Oberg and Bergstrom did

not report the conditions of combustion but simply reported satisfactory and fullycomparable. In contrast, HCB was not detected in a series of coal fired utility boilerstested in the USA (USEPA 1998). Because a sizable fraction of coal is burned in small

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domestic units, some PeCB emissions are expected. The references cited above generallyreported several times more PeCB than HCB from combustion processes with lowconcentrations of chlorine. For the purposes of this report, half of the coal used is assumedto be burned domestically and the reported HCB emission concentration from Oberg andBergstrom will be multiplied by 5. The PeCB emission factor is calculated:

(0.07 g/std m3)*(7000 m3/ton)*(5) = 2450 g/ton or 2.45 x 10-9 kg/kg PeCB per kg coal.

Multiplying this factor by coal burned in small scale combustion yields:

(2.45 x 10-9

kg/kg)*(0.5)*(4990 x 109

kg) = 6113 kg PeCB

3.3.3 Biomass combustion

Total biomass burning in the 1990s was estimated to be 3716 million metric tons of carbonwith a chlorine content ranging from 2.4 mg/kg (tulip trees in Ohio, USA) to 9000 mg/kg(citrus leaves in Southern California) (Lobert et al. 1999). The only emission factor forPeCB from burning biomass found was that of Zimmerman where waste wood was burnedin a high temperature incinerator (Zimmerman et al. 2001). No information on PeCB

emissions from smoldering combustion or other combustion conditions was found.However, Gullet and coworkers have reported a series of studies on PCDD and PCDFemissions, expressed as international toxic equivalents (I-TEQ), from combustion ofbiomass under conditions designed to simulate agricultural burning and forest fires (Gulletand Touati 2003a; Gullet and Touati 2003b; Gullet et al. 2006). Table 3.2 summarizes theI-TEQ emissions from the different studies.

Table 3.2. Comparison of emission factors from biomass combustion studies.

Substance I-TEQ ng/kg C

emission factor

PeCB ng/kg C

emission factor

Reference

Wood 0.8* 1200 ng/kg C Zimmerman et al. 2001

Sugarcane 1.7-25** Gullet et al. 2006

Forest fire 4-30 Gullet and Touati 2003a

Straw ~1 Gullet and Touati 2003b

* Emissions converted from concentration (ng/m3) to emission factor (ng/kg C) by multiplying by 7000 m

3flue gas

per ton of wood burned, and assumes wood to be 50% carbon.** The very high emission factor, 253 ng TEQ/kg C from Hawaiian sugarcane, was not used because it seems tobe an outlier.

Several researchers have noted a correlation between the emission of PeCB and PCDD/Fsfrom waste combustion (Oberg and Bergstrom 1985; Kato and Urano 2001). Zimmermanet al. reported the average emission of PeCB was 1475 times the average I-TEQ emissionin their wood burning experiment (87 ng/m

3/0.059 ng/m

3= 1475). This ratio of PeCB to I-

TEQ is within the range, 500 to 2500 ng PeCB per ng of TEQ, reported in the studiessummarized in Table 3.1, above. Based on the I-TEQ emissions from uncontrolledbiomass burning in Table 3.2, it is reasonable to estimate the PeCB emission factor formost biomass burning is somewhat greater than that reported by Zimmerman et al. For thepurposes of this report, developing an approximate global emission inventory for PeCB, theaverage emission PCDD/Fs (I-TEQ) from combustion of biomass will be taken as 8 ng/kg Cburned. Using the PeCB/I-TEQ ratio from Zimmerman the emission factor to be used forPeCB is 11,800 ng/kg C burned. Multiplying this factor by the amount of biomass burnedyields an emissions estimate.

(11,800 ng/kg)*(3716 x 106

ton)*(1000 kg/ton) = 4.39 x 1016

ng PeCB= 43,900 kg PeCB

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3.4 PeCB from degradation of other chemicals in the environment

Dechlorination processes for HCB have been studied in the laboratory. HCB wasphotodechlorinated to PeCB in surfactant micelles (Chu et al. 2002). The PeCB thus

formed was subsequently dechlorinated at about the same rate as HCB. Therefore anegligible net production of PeCB is expected from this environmental process. Indirectphotolysis of HCB in arctic lake water was reported to be facilitated by dissolved organicmatter; however there was no mention of the products (Grannas et al. 2003).

Anaerobic biological dechlorination of HCB to PeCB followed by dechlorination of PeCBhas been reported by many workers (Tiedje et al. 1987; Fathepure et al. 1988; Pardue etal. 1993; Ramanand et al. 1993; Beurskens et al. 1994; Pavlostathis and Prytula 2000).However, the dechlorination rate of PeCB is reported to be faster than that of HCB so thatPeCB does not accumulate but is further dechlorinated to tetrachlorobenzenes and lowerchlorobenzenes. Thus anaerobic biological dechlorination of HCB is not expected to leadto a net accumulation of PeCB in the environment.

Pentachloronitrobenzene (PCNB) has been reported to degrade in soil forming a smallyield of PeCB along with much higher yields of other related compounds (Beck and Hansen1974) . PCNB has also been reported to be photolyzed to PeCB along with other relatedcompounds (Crosby and Hamadmad 1971). Global agricultural use of PCNB in the 1990swas reported to be 880,590 kg (Landell Mills Market Research 1996). Thus there is thepotential for the release of some PeCB. PeCB from this source was not included in thesummary of PeCB sources, Table 3.3, because the available information did not allowcalculation of the potential quantity.

3.5 PeCB global emissions inventory

Using the factors and logic described above, the estimated global emissions of PeCBaround the year 2000 are summarized in Table 3.3, 85,000 kg/y. As described above thereis considerable uncertainty about the size of each of these estimated PeCB emissions,potentially an order of magnitude. Global emissions are clearly dominated by combustionsources. Of all sources, combustion of biomass (43,900 kg/y), combustion of solid waste(32,740 kg/y) and combustion of coal (6,113 kg/y) represent the three largest emissions.Industrial sources are relatively minor and improvements in industrial practices haveprobably led to the reductions in environmental concentrations of PeCB noted in Section 4.

Table 3.3. Summary of estimated annual global emissions of PeCB.

PCB use losses 373 kg

Chlorinated solvents

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4 Concentrations and trends of PeCB in theenvironment

4.1 Atmosphere

During a project to monitor PeCB and other chemicals in the Canadian atmosphere to lookfor seasonal changes in 1988-1989, PeCB was detected in 133 out of 143 samples (Hoff etal. 1992). Its mean concentration was reported as

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PeCB has also been monitored in the St. Clair River (Chan 1993). Concentrations of PeCBin the St. Clair River were greater at the mouth than at the head, and the mean PeCBconcentration at the mouth dropped between 1988 and 1989. Both of these monitoringprograms have continued but more recent data is not expected to be available until 2007(Neilson 2006).

A survey of Great Lakes water to determine concentrations of chlorobenzenes in water andsediments was carried out April-November 1980 (Oliver and Nicol 1982). PeCB was notdetected at some of the open water sites and mean

Figure 4.1. PeCB in Niagara Bar sediment and Niagara River suspended solids. Durhamand NYDEC data are from sediment cores and Williams data is from suspended solids.Note logarithmic concentration scale.

1

10

100

1000

1900 1920 1940 1960 1980 2000

Year

PeCBng/g

Durham

NYDEC

Williams

concentrations of PeCB were reported to be 0.2 ppt (part per trillion) in Lake Ontario and0.04 ppt in Lake Huron. Water samples collected in the spring of 1986 in the CanadianGreat Lakes showed detectable PeCB in many samples (Stevens and Neilson 1989).None was detected in Lake Superior at a detection level of 0.007-0.011 ng/L. In LakeHuron PeCB was detected in 11% of the samples with an average concentration in thosesamples of 0.033 ng/L, and in Georgian Bay PeCB was detected in 29% of the samples atan average concentration of 0.019 ng/L. In the lower Great Lakes, concentrations wereonly a bit higher, 14% detected in Lake Erie with an average of 0.058 ng/L and in LakeOntario 70% detected with an average PeCB concentration of 0.062 ng/L. Water sampling

results in the mid to late 1990s were statistically treated to calculate the upper 90%confidence interval of compounds like PeCB which were only detected part of the time(Williams et al. 2001). Thus the upper 90% confidence interval reported for Lake Superiorin 1997 was 0.024 ng/L PeCB; Lake Erie in 1998 was 0.02 ng/L; and Lake Ontario in 1998PeCB was 0.05 ng/L.

Precipitation has been monitored on the Canadian side of the Great Lakes forcontamination by organochlorine compounds, including PeCB (Chan et al. 2003). PeCBwas detected in less than 50% of samples so that total amounts of these compounds couldnot be calculated. A study of PeCB in snow and ice from the Russian arctic reported onlytraces (Melnikov et al. 2003). In southeast Africa, on the shore of Lake Malawi, PeCBconcentrations in precipitation samples collected in 1997 and 1998 ranged from 1 to 48pg/L with an average of 1014 pg/L (Karlsson et al. 2000).

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A 1993 study of the distribution of chloroorganics in the North Pacific Ocean, the Beringand Chukchi Seas found PeCB in all samples (Strachan et al. 2001). PeCB concentrationswere an average of 16 pg/L in the dissolved phase. Suspended solids represented just asmall fraction of the total PeCB, adding 0.38 pg/L. Strachan et al. calculated that the flowof water northward into the Arctic Ocean carries 0.31-0.52 metric ton of PeCB per year.

Water and sediment in the Yangtse River near Nanjing were analyzed for organochlorinesin 1998 (Jiang et al. 2000). The total PeCB concentrations were about 0.4 ng/L in the riverwater. An average of 57% of the PeCB was in the dissolved phase and on particulate

matter less than 0.7 m. The highest sediment concentration of PeCB at one location was3 ng/g. Water from four rivers draining industrial regions in the U.K. were sampled weeklyfor two years to determine the chlorobenzenes contributed to the Humber estuary (Meharget al. 2000). The flux of chlorobenzenes into the Humber was dominated by 1,2-dichlorobenzene, 56 kg/year, and 1,4-dichlorobenzene, 65 kg/year, with only 0.8 kg/year ofPeCB discharged.

4.3 Sediments

Sediment cores from Lake Ontario near the mouth of the Niagara River reveal a history ofPeCB loading to Lake Ontario which parallels that of the other chlorobenzenes andchlorinated chemicals. Figure 4.1 shows PeCB reached its peak concentration about 1960followed by a substantial decline to about 10% of the peak by 1980 (Durham and Oliver1983; NYDEC 1998) in this industrially impacted area. Concentrations of PeCB onsuspended solids in the Niagara River flowing into Lake Ontario have continued to dropduring the 1990s as shown by suspended solids analyses (Williams et al. 2000). It isinteresting to note how well the PeCB concentrations on suspended solids agree with theconcentrations in sediment cores. Note also that this more recent concentration trend isthe same as observed in the earlier sediments.

Kaminsky et al. analyzed sediment samples collected from a number of sites in westernLake Ontario in October 1980 to trace the movement of contaminants from the NiagaraRiver (Kaminsky et al. 1983). PeCB concentrations ranged from 2 ppb to 32 ppb. Inanother study the distributions of organochlorines in Lake Ontario sediments were studiedto estimate total quantities which had accumulated in surface sediments as of 1981 (Oliveret al. 1989). At that time they estimated a total inventory of about 3 metric tons of PeCB inLake Ontario surface sediments. Surface sediments in Lakes Erie, Huron, and St. Clairwere analyzed for chlorobenzenes and other chlorinated chemicals in 1980 and 1982(Oliver and Bourbonniere 1985). Mean PeCB concentrations in sediments in SouthernLake Huron were 1.5 ng/g, Lake St. Clair 5.8 ng/g, Western Lake Erie 2.9 ng/g, CentralLake Erie 1.0 ng/g, and Eastern Lake Erie 0.9 ng/g. The implication is that one source ofPeCB was along the St. Clair River and perhaps another along the Detroit River.

Muir et al. have determined the concentrations of PeCB in the sediment of a series ofremote lakes in northern Canada (Muir et al. 1995). Sediment surface layer concentrations(representing a period of time approximately centered on 1979-1988) of PeCB in thesenorthern lake sediments ranged from less than 0.01 to 0.73 ng/g sediment. Table 4.1summarizes these results. The PeCB concentrations have been divided by the fraction oforganic carbon (OC) in the sediments to allow comparison with regulatory limits. Thesediment PeCB concentrations found in four Alaskan Arctic lakes sampled in 1991-1993averaged 0.10 0.10 ng/g dry weight, approximately the same as the Canadian lakesdescribed in Table 4.1 (Allen-Gil et al. 1997).

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Table 4.1. Concentration of PeCB in remote Lake Sediments in Northern Canada(Muir et al. 1995).

Lake PeCB ng/g % OC PeCB ng/g OC

Lake 375 0.28 13.4 2.1

Lake 382

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Low concentrations of PeCB, 0.01 to 0.06 g/kg were reported in sediment from theindustrially polluted Kishon River, Israel (Oren et al. 2006). As in many of the studies,concentrations of PeCB were correlated with the organic carbon content of the sediment.Surface sediments in Masan Bay, Korea, were analyzed in 1997 for chlorinated compounds(Hong et al. 2003). PeCB was detected in only a few samples at up to 0.28 ng/g.

4.4 Soils

The concentrations of chlorobenzenes in surface soil at five sites in the Niagara Falls(USA) area were studied (Ding et al. 1992). The five sites were chosen to show ifsignificant quantities of chlorobenzenes were migrating through the air from the Love Canalhazardous waste site or accumulating from contaminated water. The site near Love Canalwas compared with nearby industrial sites and a suburban site 12 miles from the canal.PeCB was detected in soil samples from all the sites. Concentrations in individual soilsamples ranged from non detect up to 1700 pg/g. The suburban site had a mean PeCBconcentration of 480 pg/g with a range of 180 to 1200 pg/g. The conclusion was that the

Love Canal hazardous waste site had not released excessive amounts of chlorobenzenesto the atmosphere which deposited in the region.

The European Reference Soil-Set was analyzed for a variety of chemicalmicrocontaminants including PeCB (Gawlik et al. 2000). PeCB concentrations in the fivesoils ranged from 0.10 to 0.79 ng/g. Analysis of digested sewage sludges from fivewastewater treatments near Vancouver (Canada) to determine their suitability for

application to cropland did not detect PeCB at a detection level of

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Figure 4.2. Concentrations of PeCB in herring gull eggs from colonies on the shores of theGreat Lakes. Note the logarithmic concentration scale. Concentrations less than the limitof quantitation (LOQ) have been plotted as 0.5 the LOQ. The trend lines for eggs from

Lakes Superior and Ontario show the average rate of decrease in PeCB concentration.

y = 3E+165e-0.1907x

y = 6E+126e-0.1462x

0.1

1.0

10.0

100.0

1000.0

1970 1980 1990 2000 2010

Year

PeCBng/g

Ontario

Michigan

Superior

Expon. (Ontario)

Expon. (Superior)

LOQ 1 ng/g

Analyses of PeCB and other chloroorganics in Lake Ontario biota and environmentcollected 1981-1986 enabled determination of bioconcentration and biomagnificationfactors (Oliver and Niimi 1988). The concentrations of PeCB are listed in Table 4.3.

Table 4.2. Great Lakes herring gull colonies and rates of PeCB concentration decrease inherring gull eggs for the entire period of monitoring through 2004. See the CWS reportscited above for exact dates and monitoring sites.

Location Rate Constant(Year

-1)

Percent Decrease(Year

-1)

Half-life

(Years)

St Lawrence R., Strachan Island -0.071 6.9 9.8

Lake Ontario, Snake Island - WestBrothers Island

-0.14413.4 4.8

Lake Ontario, Muggs Island - LeslieSpit

-0.19117.4 3.6

Hamilton Harbor -0.112 10.6 6.2

Niagara River -0.167 15.4 4.1

Lake Erie, Colbourne Light -0.149 13.8 4.7

Lake Erie, Middle Island -0.115 10.9 6.0

Detroit River, Fighting Island -0.158 14.6 4.4

Lake Huron, Chantry Island -0.107 10.1 6.5

Lake Huron, Channel Shelter I. -0.173 15.9 4.0

Lake Huron, Double Island -0.136 12.7 5.1

Lake Michigan, Gull Island -0.111 10.5 6.2

Lake Michigan, Big Sister Island -0.105 10.0 6.6

Lake Superior, Agawa Rock -0.146 13.6 4.7

Lake Superior, Granite Island -0.12111.4 5.7

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A survey of Great Lakes fish caught during the late 1970s found PeCB only in fish fromLake Ontario and the Ashtabula River, Ohio, and its tributary (Kuehl et al. 1981). Morerecently the US National Study of Chemical Residues in Fish (Kuehl et al. 1994) detectedPeCB at about 22% of the 388 sites nationwide, with the highest concentrations nearchemical manufacturing plants. Pereira et al. and Burkhard et al. reported PeCB along with

other halogenated organics in biota and sediments from the lower Calcasieu River and theBayou dInde, Louisiana (Pereira et al. 1988; Burkhard et al. 1997). A 1993 study ofcontaminants in brown bullhead fish from the Detroit River, Michigan found PeCB alongwith much higher concentrations of PCBs and other chloroorganics in this industriallyimpacted river (Leadley et al. 1998). Mean concentrations of PeCB were 13.0, 29.4 and

16.1 g/kg wet weight in the fish from Amherstburg Channel (east side), Trenton Channel

(west side) and Peche Island at the head of the river, respectively.

Table 4.3. Concentrations of PeCB in Lake Ontario biota and environment (Oliverand Niimi 1988).

Species, units PeCB

Water, pg/L 7215

Bottom sediments, ng/g dry wt. 3314Suspended sediments, ng/g dry wt. 133.9

Plankton, ng/g wet wt. 0.60.3

Mysids, ng/g wet wt. 8.46.5

Amphipods, ng/g wet wt. 5.03.7

Oligochaetes, ng/g wet wt. 0.80.3

Sculpin, ng/g wet wt. 2.6

Alewive, ng/g wet wt. n.d.

Small smelts, ng/g wet wt. n.d.

Large Smelts, ng/g wet wt. 2.1

Fish (large salmonids), ng/g wet wt. 5.03.1

Zebra mussels and eel in the Rhine and Meuse Rivers in 1994 were analyzed for a widevariety of chemicals and metals (Hendriks et al. 1998). PeCB concentrations in zebra

mussels from the Rhine, Meuse, and Ysselmeer were 0.49, 0.27, 0.50 g/kg wet weight,

respectively. PeCB in eel from the Rhine, Meuse, and Hollands Diep were 15, 2.9, and 7.7

g/kg wet weight, respectively. A survey of chemicals in fish from the Ebro River in Spain

detected PeCB in 14 out of 18 samples with an LOD of 0.30 g/kg. The meanconcentration of PeCB was 1.10 g/kg with a range of 0.32 to 3.31 g/kg (Lacorte et al.2006).

A quantity of PeCB, estimated at 59 kg, mixed in 5400 kg of PCB heat transfer fluid wasreleased in the Gulf of St. Lawrence after a barge sank in 1970 (King et al. 2003). Thebarge was raised in 1996 at which time it was discovered that much of the heat transferfluid had leaked into the environment. Snow crab digestive glands were monitored for their

PeCB content and showed a rapid decline over the five year period at the sampling pointright where the barge had rested. Concentrations were 150 ng/g wet weight in 1996, 12ng/g wet weight in 1997, 3.6 ng/g wet weight in 1998, 3,6 ng/g wet weight in 1999, 3.1 ng/gwet weight in 2000. The other sampling sites, one or more miles distant, showed noincreased concentrations over what is apparently the PeCB background concentration inthat region, even in 1996.

A study of organochlorines in fin whale blubber collected in 1971 and 1972 from theNewfoundland area showed mean concentrations of PeCB of 0.96 and 0.01 ng/g lipid forfemales and males, respectively (Hobbs et al. 2001). From Nova Scotia the concentrationswere 0.23 ng/g lipid and non detected for females and males, respectively. Because HCBwas still in wide use in agriculture at that time, the corresponding concentrations of HCBwere 244 and 333 ng/g lipid for females and males from Newfoundland and 217 and 221

ng/g lipid for females and males from Nova Scotia. Blubber biopsies from St. LawrenceEstuary beluga whales in 1994-1998 showed PeCB concentrations ranging widely from

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1.56 ng/g lipid to 1510 ng/g with a geometric mean of 24.5 in females (Hobbs et al. 2003).In males the range was similar, 1.5-1500 ng/g lipid with a geometric mean of 144 ng/g.

A study of PeCB in fish from four Alaskan arctic lakes found mean concentrations (ng/g wetweight) of PeCB of 1.421.82 in grayling liver, 0.060.08 in grayling muscle, 0.480.35 in

lake trout liver and 1.213.66 in lake trout muscle (Allen-Gil et al. 1997). A terrestrial toppredator, the arctic fox has been studied for accumulation of chlorinated chemicals(Hoekstra et al. 2003). Samples were collected at three sites: Arviat on Hudson Bay,Canada, Holman, Northern Territory, Canada and Barrow, Alaska. About 20 animals ateach site were collected during 1999-2001 at some distance from human habitation tominimize effects of garbage scavenging. The PeCB concentrations found in arctic foxeswere: Arviat, muscle, 0.610.12; Holman, muscle, 0.290.06; Holman, liver, 0.570.11;Barrow, muscle, 0.550.20; Barrow, liver, 0.730.17.

The polar bear has been studied as another top predator whose diet allows foraccumulation of persistent chemicals. A wide ranging study of bears from Alaska, Canada,East Greenland and Svalbard sampled between 1996 and 2002 looked for geographicalvariations in chemical concentrations (Verreault et al. 2005). Unfortunately for this purpose

the data was reported in terms of HCB and the sum of PeCB, HCB and 1,2,3,4-tetrachorobenzene (TeCB). Thus only the sum of PeCB and TeCB can be calculatedwhich can be interpreted as an upper bound on the PeCB concentration. HCB constitutedabout 75% of the sum of these three chlorobenzenes. Table 4.4 shows the reportedconcentrations and the sum of TeCB and PeCB. Concentrations of chlorobenzenes wererelatively uniform between these polar bear populations spread over about half of the arctic.

Body burdens and concentrations of chlorobenzenes in polar bears of different ages havebeen studied before and after their seasonal fasts (Polischuk et al. 2002). Polischuk et al.reported that none of the chlorobenzenes included in their summation (1,2,4,5-TeCB,PeCB, and HCB) were excreted or metabolized during the fast so that concentrationsincrease as fat was metabolized. They also reported that nursing polar bear cubs receivedincreased amounts of chlorobenzenes so that the concentration of chlorobenzenes in cubs

is greater than that in adult bears.

Table 4.4. Concentrations of chlorobenzenes in polar bear lipid from adipose tissue,geometric mean in ng/g lipid (range) (Verreault et al. 2005).

Location CBz HCB PeCB+TeCB

calculated

Alaska (males) 113 (70.4-181) 84.5 (35.1-157) 28.5

Alaska (females) 118 (70.0-277) 85.7 (41.7-230) 32.3

Amundsen Gulf 113 (71.1-190) 75.5 (43.9-146) 37.5

W. Hudson Bay 97.5 (55.9-257) 75.3 (39.3-229) 22.2

Foxe Basin/Gulf of Boothia 127 (73.4-329) 87.3 (46.3-305) 39.7

Lancaster Sound/Jones Sound 148 (111-186) 107 (74.9-146) 41

N. Baffin Island 191 (108-656) 152 (76.7-620) 39

S. Baffin Island 111 (42.0-275) 87.1 (33.2-249) 23.9

E. Greenland 79.1 (36.5-323) 60.0 (25.5-311) 19.1

Svalbard 105 (49.0-248) 90.4 (37.9-229) 14.6

Chlorobenzenes and other organochlorine compounds have been determined in a variety

of Greenland biota collected in 1998-2001 (Vorkamp et al. 2004). As above, only theconcentrations of HCB and the sum of 1,2,3,4-TeCB, PeCB and HCB are reported so thatthe sum of TeCB and PeCB have been determined by difference. As shown in Table 4.5,

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the concentration of PeCB+TeCB in lipid is much less than that of HCB in most cases. Theconcentration of PeCB+TeCB is very small in most tissues when they are adjusted for thelipid content of the tissues. In most species the chlorobenzenes concentration in lipid isabout the same in the different tissues.

Table 4.5. Median concentrations and ranges of chlorobenzenes concentrations inGreenland biota in ng/g lipid weight (Vorkamp et al. 2004). The percentage of lipid intissues was used to calculate the wet weight concentration of PeCB+TeCB, the potentialPeCB dose to predators from consumption of prey.

Species Tissue % Lipid CBz, ng/g lw HCB, ng/g lw PeCB+TeCB, ng/g lw

PeCB+TeCB, ng/g ww

Ptarmigan Liver 6.7 6.6 (4.3-29) 2.9 (2.1-5.1) 3.7 0.248

Muscle 3.8 5.4 (3.5-9.6) 3.6 (3.5-6.8) 1.8 0.068

Hare Liver 4.0 170 (120-330) 170 (120-330) 0 0.000

Muscle 3.1 12 (3.1-56) 9.9 (3.0-40) 2.1 0.065

Kidney 36 17 (15-170) 17 (15-170) 0 0.000

Lamb Liver 9.1 4.8 (1.8-16) 4.6 (1.7-16) 0.2 0.018

Muscle 8.8 1.5 (0.65-4.4) 1.2 (0.53-3.6) 0.3 0.026Kidney 3.9 5.4 (3.1-12) 4.8 (2.9-11 0.6 0.023

Blubber 91 0.24 (0.11-0.48) 0.21 (0.089-0.41) 0.03 0.027

Caribou Liver 7.3 6.3 (3.9-7.6 6.2 (3.9-7.4) 0.1 0.007

Muscle 1.5 9.1 (7.0-10) 8.7 (6.8-9.5) 0.4 0.006

Kidney 3.4 3.8 (2.3-5.6) 3.7 (2.2-5.4) 0.1 0.003

Blubber 64 7.5 (3.8-9.6) 7.3 (3.7-9.3) 0.2 0.128

Muskox Liver 9.8 150 (46-190) 150 (45-190) 0 0.000

Muscle 2.0 620 (23-1100) 620 (23-1100) 0 0.000

Kidney 3.1 180 (4.9-460) 180 (4.3-460) 0 0.000

Blubber 89.8 0.79 (0.29-7.7) 0.46 (0.13-6.2) 0.33 0.296

Arctic char Muscle 1.1 29 (18-75) 28 (18-48) 1 0.011

(From three Muscle 1.5 52 (37-110) 49 (36-88) 3 0.045

Locations) Muscle 2.8 28 (19-53) 25 (17-48) 3 0.084

Shrimp Muscle 0.95 75 (41-110) 15 (12-19) 60 0.570

Snow crab Liver 4.0 49 (27-66) 40 (21-53) 9 0.360

Muscle 0.72 63 (38-86) 45 (25-55) 18 0.130

Icelandscallop

Muscle 0.40 1.8 (0.80-3.3) 0.44 (n.d.-1.2) 1.36 0.005

Atlantic cod Liver 58 30 (28-33) 27 (25-30) 3 1.740

Muscle 0.68 38 (18-71) 33 (16-49) 5 0.034

Redfish Muscle 1.8 38 (20-45) 34 (19-39) 4 0.072

Atlanticsalmon

Muscle 9.2 16 (14-24) 13 (11-18) 3 0.276

Greenland

halibut

Liver 39 48 (39-730) 42 (34-710) 6 2.340

Muscle 10 51 (24-62) 44 (19-54) 7 0.700

Wolffish Liver 21 38 (27-58) 34 (24-53) 4 0.840

Muscle 1.7 42 (26-60) 37 (23-54) 5 0.085

Capelin Muscle 1.7 51 (37-79) 47 (35-73) 4 0.068

Shorthornsculpin

Liver 17 60 (45-110) 52(39-94) 8 1.360

Shorthornsculpin

Liver 23 53 (39-110) 44 (34-91) 9 2.070

Shorthornsculpin

Liver 15 16 (10-37) 14 (8.7-32) 2 0.300

Shorthornsculpin

Liver 10 17 (13-26) 14(12-22) 3 0.300

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Species Tissue % Lipid CBz, ng/g lw HCB, ng/g lw PeCB+TeCB, ng/g lw

PeCB+TeCB, ng/g ww

Commoneider

Liver 5.0 81 (45-89) 71 (38-75) 10 0.500

Muscle 3.5 60 (42-110) 50 (36-90) 10 0.350King eider Liver 5.3 65 (49-130) 56 (42-110) 9 0.477

Muscle 3.5 73 (52-120) 62 (45-100) 11 0.385

Kittiwake Liver 5.7 13 (9.4-30) 2.2 (1.0-6.3) 10.8 0.616

Muscle 14 20 (9.6-71) 3.6 (0.57-44) 16.4 2.296

Thick-billedmurre

Liver 5.5 110(77-170) 97 (69-150) 13 0.715

Muscle 3.6 89 (46-360) 76 (41-320) 13 0.468

Ringed seal Liver 5.4 20 (13-34) 12 (8.9-17) 8 0.432

Muscle 12 20 (9.4-71) 13 (6.7-29) 7 0.840

Blubber 97 16 (1.1-60) 9.3 (0.65-27) 6.7 6.499

Ringed seal Liver 5.3 11 (7.0-22) 5.2 (4.1-16) 5.8 0.307

(Second Muscle 3.2 11 (6.9-43) 7.6 (5.2-14) 3.4 0.109

Location) Kidney 3.8 10 (4.7-18) 5.4 (2.7-11) 4.6 0.175

Blubber 92 14 (8.6-39) 7.9 (5.0-13) 6.1 5.612

Harp seal Liver 6.2 78 (21-250) 72 (13-250) 6 0.372

Muscle 1.7 58 (15-140) 48 (12-120) 10 0.170

Kidney 3.0 21 (12-52) 19 (9.5-48) 2 0.060

Blubber 87 71 (14-120) 66 (11-110) 5 4.350

Minke whale Liver 5.8 170 (150-250) 170 (150-250) 0 0.000

Muscle 1.2 120 (71-240) 120 (71-240) 0 0.000

Kidney 3.4 120 (52-250) 120 (52-250) 0 0.000

Blubber 18 n.a. 160 (15-610) n.a.

Beluga Liver 6.3 210 (40-410) 190 (34-380) 20 1.260

Muscle 1.8 370 (210-570) 350 (190-510) 20 0.360

Kidney 3.2 250 (31-360) 230 (26-310) 20 0.640Skin 3.6 160 (16-320) 150 (15-310 10 0.360

Blubber 88 260 (27-690) 250 (21-550) 10 8.800

Narwhal Liver 4.7 430 (290-810) 420 (280-780) 10 0.470

Muscle 2.2 450 (50-800) 440 (45-770) 10 0.220

Kidney 2.5 400 (180-470) 390 (170-450) 10 0.250

Skin 3.5 310 (250-410) 300 (240-390) 10 0.350

Blubber 87 490 (390-830) 470 (370-790) 20 17.400

An extensive study of organochlorine compounds in seals from the east and west sides ofthe Northwater Polnya between Canada and Greenland looked for influences of diet (Fisket al. 2002). Tissue samples from the ringed seals were collected by Inuit hunters during

the spring of 1998. Fisk et al. reported 8.41.1 ng/g wet weight in females and 7.31.9ng/g PeCB in males from the west side, Grise Fiord. On the east side, Qanaq, femalescontained 5.00.5 and males 7.01.5 ng/g wet weight of PeCB.

A study of organochlorine concentrations in seal blubber, fishes and invertebrates from theWhite Sea in Northwestern Russia found PeCB along with other compounds (Muir et al.2003). The mean concentrations of PeCB in the different species are shown in Table 4.6.Harp seal pups collected in 1992 and 1998 were analyzed to look for trends incontamination. The mean concentration ( standard deviation of the 10 samples) of PeCBin 1992 was 112.0 ng/g lipid weight. In 1998 the concentration of PeCB was 5.01.8 ng/glipid weight. Apparently, the concentrations of PeCB dropped by approximately 50% overthe period of 1992 to 1998 as did concentrations of nearly all the other organochlorinesmeasured.

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Table 4.6. Mean concentrations of PeCB in seal blubber, fish and invertebrates fromthe White Sea, Russia (Muir et al. 2003).

PeCB

Bearded seal blubber 0.9 ng/g lipid

Harp seal (adult) blubber 12 ng/g lipid

Ringed seal (juvenile) blubber 2.5 ng/g lipid

Ringed seal female blubber 2.9 ng/g lipid

Ringed seal male blubber 2.1 ng/g lipid

Navaga whole fish 5.06 ng/g wet wt.

Bullrout whole fish 0.01 ng/g wet wt.

White Sea cod muscle 0.01 ng/g wet wt.

White Sea herring whole fish 3.77 ng/g wet wt.

Smelt whole fish 3.81 ng/g wet wt.

Isopod 0.04 ng/g wet wt.

Zooplankton 0.07 ng/g wet wt.

Spider crab 0.08 ng/g wet wt.

Whelk

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Consider the northern hemisphere as a continuous stirred pot reactor. The volume of theatmosphere can be calculated from its depth, 8000 m (Weast 1983) and the area of thenorthern hemisphere, 255 million km

2. If the concentration of PeCB in the atmosphere is

45 pg/m3, then the total amount of PeCB in the atmosphere can be calculated:

NH atmosphere (255 x 106

km2)*(8000 m)*(10

6m

2/km

2) = 2.04 x 10

18m

3

PeCB (45x10-12 g/m3)*(2.04 x 1018 m3) = 91,800,000 g PeCB

The globally, seasonally, diurnally averaged atmospheric half-life of 370 days is equivalentto a first order reaction rate of 0.69 y

-1, see Section 2.1 above. Thus the amount of PeCB

that needs to be added to the atmosphere to maintain a concentration of 45 pg/m3

is:

0.69 y-1

* 91,800 kg = 63,200 kg/y.

This is about the same as found in the bottom-up inventory based on sources reported inthe literature, section 3. This calculated number of 63,000 kg/y ignores any degradation ofPeCB dissolved in water, sorbed to soil or sediments or exported irreversibly to polarregions and across the equator. Inclusion of the additional fates for PeCB as done by theEMEP environmental model (Vulykh et al. 2005) would increase the amount needed to

maintain the atmospheric concentration. It is important to be aware of the uncertaintiesinvolved in all aspects of these calculations, PeCB emissions, modeling simplifications andenvironmental concentrations. The surprisingly close agreement between the calculatedemissions and the calculated total degraded suggests that there are no major hiddenemission sources which are dramatically affecting environmental concentrations of PeCB.

Because only atmospheric degradation has been considered, it is conservative in that theinclusion of additional degradation processes will increase the overall degradation rate.Because only published sources of emissions of PeCB in the environment have beenincluded there could be additional sources which have not been considered. The assumedatmospheric PeCB concentration is based on only one study (Shen et al. 2005), and it isgenerally consistent with the higher concentrations reported from some of the other studiesof PeCB in the atmosphere.

4.7 PeCB in the Environment Summary

PeCB has been observed at low concentrations essentially everywhere in theenvironment that has been carefully analyzed.

Polar bear adipose tissue had the highest reported concentrations of PeCB+TeCBwith an average concentration of 30 ng/g lipid.

Among the highest reported PeCB concentrations in prey organisms (e.g. for polarbears) is about 5 ng/g wet weight in the blubber of Arctic seals.

PeCB concentrations in herring gull eggs on the shore of Lake Superior, Canada

have dropped by over 90% since the 1970s.

Concentrations of PeCB have dropped by over 90% since the 1960s in sedimentsnear the industrially impacted Niagara Falls area of the US and Canada.

PeCB concentrations in sediments from remote lakes in northern Canada averaged0.20 ng/g compared to about 8 ng/g off the mouth of the Niagara River in LakeOntario.

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5 Ecotoxicity

5.1 Aquatic

Acute toxicity information on PeCB to aquatic organisms was summarized by van dePlassche et al. and is included in Table 5.1 (van de Plassche et al. 2001). EnvironmentCanada extrapolated from the toxicity of the lower chlorobenzenes to derive an estimate fortoxicity of PeCB to benthic organisms because there was no information on toxicity ofPeCB to benthic organisms (Environment Canada 2003). The extrapolation was based onthe observation that the chlorobenzenes appear to be non-specific in their toxic action,narcosis. That is, the toxic internal concentrations of the different chlorobenzenes tested inthe organisms, daphnids, were about the same on a molar concentration basis. Theinternal concentrations were calculated on the basis of chlorobenzenes partitioningbetween water and the daphnid. The partitioning of PeCB in sediments was also used toderive a critical toxicity value for freshwater sediments (CTVsed). The resulting CTVsed for

PeCB was 2500 g/g organic carbon (OC). In marine sediments the extrapolated CTVsedfor PeCB was 3080 g/g OC for the LOEC.

A recent detailed study on the time-dependent toxicity of PeCB to Hyalella azteca, a scud,has been published (Landrum et al. 2004). The LC50 water concentration was about 125

g/L at 28 days. The 28-day growth rate ofHyalella azteca was reduced from exposure toa water concentration of approximately 0.05 mol/L (12.5 g/L).

The toxicity of PeCB to juvenile sand crabs (Portunus pelagicus) was studied (Mortimer

and Connell 1994). They reported an LC50 of about 0.3 mol/L (75 g/L) at 96 hours, after

the crabs had molted. There appeared to be a discontinuity in the line of time versus LC50which they stated may be the result of increased sensitivity during molting. A comparisonof toxicities of a wide variety of chemicals listed the mean LC50 of two PeCB studies with

Cladocera (Daphnia) as 3218 g/L and the LC50 for PeCB withAnostraca (fairy shrimp),376 g/L (Snchez-Bayo 2006).

Fathead minnow (Pimephales promelas) embryo to early life stages were used to measurechronic toxicity of PeCB (Carlson and Kosian 1987). They reported that a concentration of

55 g/L PeCB for 32 days, which was the highest concentration that they could maintain intheir system, led to no statistically significant mortality or reduction in growth, a NOEC. The

concentration of PeCB in the minnows exposed to 55 g/L PeCB averaged 380 g/g (1.52

mol/g). They also exposed 12 juvenile minnows to 130 g/L for 6 days to look for acutetoxicity. Only one minnow died during the experiment but some of the others showed lossof equilibrium after 48 hours. Another study of toxicity and the critical body burden (CBB)

of PeCB in fathead minnows reported an LC50 between 200 and 250 g/L at both 12 and

28 days (Schuler et al. 2007).

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Table 5.1. Toxicity of PeCB to aquatic organisms.

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5.2 Plants

Lettuce (Lactuca sativa) was grown in soil containing PeCB. A 14-day study indicated anEC50 of 280 g/g and an NOEC of 50 g/g for growth (Environment Canada 1993).

5.3 Wildlife

No wildlife toxicity reports were found. A detailed review of mammalian toxicity is beyondthe scope of this report. However, both the USEPA and Environment Canada haveinterpreted key animal studies to derive a daily intake of PeCB deemed safe for the generalhuman population including sensitive subpopulations for lifetime exposure. The USEPA

Integrated Risk Information System (IRIS) has derived an RfD (reference dose) of 0.8 g/kgbw/day (USEPA 1988). This value was taken from a subchronic study on rats (Linder et al.1980). The lowest effect dose was divided by a factor of 10 to correct it for chronic toxicity,a factor of 10 to drop it to the no effect level, a factor of 10 to extrapolate to humans andother species and a final factor of 10 to protect sensitive subpopulations. Environment

Canada derived a Tolerable Daily Intake (TDI) for PeCB of 0.5 g/kg bw/day (EnvironmentCanada 1993). This TDI was based on a subchronic study in mice (McDonald 1991) withan adjustment factor of 10,000 applied to the lowest observed effect dose, 5.2 mg/kgbw/day, to protect the general human population.

5.4 Soil toxicity

The toxicity of PeCB to two species of earthworms, Eisenia andreiand Lubriculus rubellus,was determined in two different soils (van Gestel et al. 1991). ForEisenia andreithe 14day LC50s were 134 (>100 180 150

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Apart from reducing the uncertainty of identifying safe levels as compared to standard testsusing ambient concentrations, an additional advantage is that the CBB method can be usedto compare biomonitoring results for chemicals with potential for adverse effects in theenvironment (McCarty and Mackay 1993). In this chapter, we consider available bodyburden data from the literature and attempt to calculate a value for CBB for PeCB that can

be compared with existing biomonitoring data. Table 5.2 summarizes CBB data which werecollated by (Jarvinen and Ankley 1999). Studies are described individually due to technicalvariations in design.

Recently, Schuleret al. (2007) studied the CBB of PeCB in a fish, the juvenile fatheadminnow (Pimephales promelas). They found the LBB for 50% mortality to be 1.26 mmol/kgwhole body wet weight and the lowest-observed-effect CBB to be 0.66 mmol/kg for reducedgrowth rate over 28 days. For comparison with monitoring data, these values can be

converted to g/g by multiplying by the molecular weight of PeCB, 250.34. The CBB results

for this study are 315 g/g and 165 g/g for 50% mortality and reduction in growth rate,respectively.

Further studies on fish support this recent study. An early life stage study on fathead

minnow (Pimephales promelas) embryos carried out over a period of 31 days, to measurechronic toxicity of a series of chlorobenzenes, failed to observe lethality or any statistically

significant effects on growth at the highest achievable water concentration of 55 g/l (16

g/l) for PeCB (Carlson and Kosian 1987). At the conclusion of the study, the concentration

of PeCB in the whole fish was 1.52 mmol/kg. As no effects were observed the CBB valuecan be considered as greater than 1.52 mmol/kg.

Acute values from the same study after 6 days exposure of the fish to 130 g/l PeCB led to

a whole body PeCB concentration of 0.23 mmol/kg. During this test one fish died and fiveout of twelve exhibited loss of equilibrium. No further mortalities or effects were observed.The authors recalculated the body burdens of fish in both chronic and acute testsnormalized to 1% lipid. These were found to be twice as high in the acute test (1.16mmol/kg) as in the chronic study (0.63 mmol/kg) but the reason for the ten-fold lower lipid

concentration measured in acutely exposed fish than in all other tissues analysed was notexplained.

In a further study on PeCB using fish (Van Hoogen and Opperhuizen 1988) LBBconcentrations on dead guppies (Poecilia reticulata) were reported to be 2.540.59mmol/kg after 4 days exposure and 2.110.39 mmol/kg after 8 days exposure. These

concentrations resulted from exposure of the fish to 135 g/l and 100 g/l PeCB in aqueoussolution, respectively. These concentrations were achieved by using a generator column tomaximize solubility.

Monitoring data of water concentrations in Lake Ontario were used to predict tissue levelsfor 250 g sub-adult rainbow trout (Salmo gairdnerinow Oncorhynchus mykiss) fromlaboratory based BCFs of PeCB (Oliver and Niimi 1983). An average body burden of0.00087 mmol PeCB /kg was found in fish from this BCF test further to exposure to 9.37.6ng/l PeCB in a mixture of chlorobenzenes for 105 days. No adverse effects were observedat this concentration.

Several invertebrate studies have provided results comparable to those in fish. A recentstudy reported the CBB of PeCB associated with 50% mortality and growth of theamphipod, Hyalella azteca, over an exposure period of 1 to 28 days (Landrum et al. 2004).

The organisms were exposed to radiolabeled PeCB in acetone (100 l/l), diluted to between

4.8 and 920 g/l, in a semi-static test with partial (chronic exposure) or total (short termexposure) replacement of test solutions every 1-2 days. The highest concentrationsemployed are probably well above the solubility level of the substance in water. Similarresults were found regardless of whether the body burden values were based on living or

dead organisms. Short term exposure (1 to 2 days) resulted in LBBs from 1 to 3 mmol/kgwhile exposure from 10 to 28 days led to LBBs ranging from 0.4 to 0.5 mmol/kg. Astatistically significant reduction in growth rate after 28 days exposure was observed

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starting at whole body concentrations of approximately 0.15 mmol/kg so the CBB can bebased on the no observed effect body concentration for growth of 0.1 mmol.kg.

In the marine environment the lethal body burden of PeCB was studied for juvenile sandcrabs (Portunus pelagicus) (Mortimer and Connell 1994). The crabs were exposed to

PeCB in seawater with a range of concentrations from 0.03 to 3 ppm in solvent(concentration unspecified) for up to approximately 1000 hours. Many of the concentrationsused were above the aqueous solubility of PeCB. The crabs molted during the test andthere was an apparent discontinuity in the LC50 versus time plot after a few days, withtoxicity increasing at molt. Mortimer and Connell stated that other authors have reportedincreased sensitivity to chemicals while molting although this is possibly related toincreased potential for uptake due to loss of the impermeable exoskeleton. They reportedtheir results as an equation for the line of LC50 versus time with results expressed in terms

ofmol/kg lipid. Extrapolating back to time = 0, the theoretical CBB was reported to be 3.24

mmol/kg wet weight. Calculating from their equation, the CBB associated with the LC50 at7 days is 0.2 mmol/kg lipid and based on the authors estimate of 0.4% lipid, 0.09 mmol/kgwet weight. This study is the only aquatic study that does not provide results that fit exactlywithin the predictive range for a mode of action I chemical (non-polar narcotics). Due to the

non-standard test method the inaccurate reporting of exposure concentration, clear effectof molting on the effect concentration, not observed elsewhere, and information andmethodological deficiencies, the results of this study should not be included to provide avalue for CBB.

One terrestrial study was found in the literature. The CBB concept was applied to toxicitytests for PeCB with earthworms (Eisenia andrei) in different exposure systems, water, soil,food and filter paper (Belfroid et al. 1993). Exposure concentrations causing mortality andtime to death varied dramatically, presumably according to the changing uptake rates fromthe medium in which the worms were placed. For PeCB mixed in soil (at 250 to 567 mg/kg)in an LBB ranging from 2.34 0.73 mmol/kg within 7 to 10 days was observed. Exposureof worms to a 0.2 mg/l water solution of PeCB resulted in a lethal CBB of 1.310.6 mmol/kgafter 1 to 7 days. Oral exposure to 60 mg/kg PeCB mixed in the manure (food) supply led

to death after 19 to 23 days. The lethal CBB was 1.460.71 mmol/kg. The surviving wormsaveraged 0.44 mmol/kg PeCB. Earthworms were exposed on filter paper treated with 75

and 7.5 g/cm2

of PeCB. Death was observed between 24 and 45 hours with a lethal CBBof 1.290.61 mmol PeCB /kg. All results fall within the expected range for LBB for non-polarnarcotics.

Conclusion on critical body burdenWhile several methods, exposure routes and species with very different feeding strategieswere used to determine the lethal and critical body burden of PeCB, remarkably similarresults were found with the exception of the non-standardised and incompletelydocumented marine study on crabs. Based on this evidence an LBB of 1 to 2.5 mmol/kg(250 to 626 mg PeCB/kg) would be expected. Based on the general knowledge onsubstances with a narcotic mode of action and the available evidence on PeCB, such as

the Hyalella growth/mortality study and other information discussed, an estimation of 0.1mmol PeCB/Kg (25 mg/kg) can be tentatively proposed as a CBB for chronic effects.

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Table 5.2. Summary of critical tissue residue data from Jarvinen and Ankley (1999).

Species

Taxonomic

group

Lofe

stage

Test

conc.

Exposure

(days)

TissueResiduemg/kg

(wet)

TissueResiduemmol/kg

(wet) Effect Reference

Eisenia andrei(Fw)

Annelidearthworm Adult 0.2 mg/l 10 325.4 1.3

Survival -Reduced -Death

Belfroid et al,1993

Portunuspelagicus (Sw)

Crustaceansand crab Juvenile

0.1-100mol/l 7 861 3.44

Survival -Reduced -Death

Mortimer andConnell, 1994

Oncorhynchusmykiss (Fw)

FishRainbowtrout

Subadult,250g

0.009g/l 105 0.22 0.0009

Survival -No effect

Oliver andNiimi, 1983

Pimephalespromelas (Fw)

FishFatheadminnow

Embryo-Juvenile

55.0g/l 31 380 1.5182

Survival,Growth -No effect

Carlson andKosian, 1987

Poeciliareticulata (Fw) Fish Guppy Adult

0.40mol/l 8 528 2.11

Survival -Reduced -Death

van HoogenandOpperhuizen,1988

Poeciliareticulata (Fw) Fish Guppy Adult

0.54mol/l 4 635.8 2.54

Survival -Reduced -Death

van HoogenandOpperhuizen,1988

Sw= Salt water, Fw=Fresh water

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6 Conclusions

The physical properties and low reactivity of PeCB in the environment suggest it is

susceptible to long range transport. PeCB has been detected in many remote environments at low concentrations

suggesting long range transport.

The primary sources of PeCB in the environment are combustion processes.

PeCB concentrations have decreased in the environment.

PeCB is bioaccumulated in aquatic organisms, but there is little biomagnification inaquatic food webs.

7 References

Ahling, B., Bjorseth, A., Lunde, G. 1978. Formation of chlorinated hydrocarbons duringcombustion of poly(vinyl chloride). Chemosphere 10: 799-806.Aittola, J.-P., Paasivirta, J., Vattulainen, A., Sinkkonen, S., Koistinen, J., Tarhanen, J. 1996.Formation of chloroaromatics at a metal reclamation plant and